Genetic tests for disease-causing and susceptibility-conferring genotypes in healthy individuals could prevent disease if safe and effective interventions were available for those with positive results. Few such interventions have yet been developed. If population-wide screening were to be undertaken, many false positives would occur for every true positive, especially for common diseases; instituting therapy would be costly, sometimes unnecessary, and possibly harmful. Thus, except for a few rare diseases for which highly sensitive and specific genetic tests and safe and effective prevention modalities are available, genetic screening will not play a major role in preventing disease. Testing in families in which particular common diseases recur might have greater validity, but most people with common diseases do not have a family history of the disease. Family testing would be a practi tioner responsibility, not a public health one.

Genetic tests for identifying healthy, heterozygous carriers of alleles for recessive diseases could be used to identify couples at risk of having fetuses with severe diseases and tests for disease-causing genotypes could be used in high risk pregnancies to detect affected fetuses, thereby providing parents with the option of abortion. Although genetic counselors in some countries place great emphasis on parental autonomy in making decisions regarding carrier and prenatal testing and pregnancy termination, even in these countries some geneticists, and others, believe that a reduction in the number of deleterious genes in the population is appropriate. Thus increase in the number of genetic tests for severe disorders for which no treatment is available, or for which treatment is very expensive, could rekindle interest in eugenics. In the United States and several western European democracies, eugenics was embraced by many people in the
early part of the twentieth century. More recently, it has been advocated in some Asian countries. It is doubtful that genetic testing and therapy based on genetic differences will ever result in a substantial reduction in the burden of disease either by preventive interventions or by eugenics. The emphasis on genetics detracts from other public health approaches that could improve health and prevent disease throughout the population instead of only in those at extreme genetic risk. The genetic approach “blames the victim” and ignores the role of society in fostering unhealthy environments and social inequities, which are major contributors to morbidity and mortality.